Techniques for Web Telerobotics - Australia's Telerobot on the Web ...

6.5 The Framework in Practice 113
Figure 6.4: The peer and router architectures shown <strong>for</strong> a single JAVA client, robot, and image capture
device. The robot server subscribes to the robot channels and executes move requests as they are received.
Access control is managed by the router. New robot states are broadcast by the robot server as the robot
is moved. The image server subscribes to the robot state channel, and takes images <strong>for</strong> each new robot
state, these images are then broadcast on the image channel. The Applet subscribes to the robot and image
channels to receive updates and to submit control requests.
of the workspace via the image control channel. Status and position of the robot are received
asynchronously over the robot state channel during task execution, as is new image data over the
image data channel. If a user fails to control the robot, then they can still receive robot state and
image updates via the robot state and image data channels. The Applet also subscribes to a chat
channel so that users may communicate with each other while controlling/watching the robot. An
example of the Applet running is shown in figure 6.5, this is a screen-shot from a second test
system setup at ABB Corporate Research, Norway.
The Applet interface shown in figure 6.5 shows a four move session controlling the robot. Robot
commands are entered and monitored using the text fields on the left side of the interface, while
the right hand side shows current images and messages sent by other users. To move the robot
the user must first gain control, then create and send robot commands. Robot commands can be